Patent EP0333467A1 successfully refreshed from Google Patents.
EP0333467A1
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Optical magnetic recording medium provided with high coercive force layer and low coercive force layer containing light rare earth
Assignee: Canon Inc
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Filing: 1989-03-16
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Granted: —
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Expires: 2009-03-16
Abstract
Abstract An optical magnetic recording medium comprises: a first magnetic layer vertically magnetizable comprising a rare earth-iron group amorphous alloy; and a second magnetic layer having lower coercive force than the first magnetic layer compriging a rare earth-iron group amorphous alloy containing light rare earth, the second magnetic layer being exchange bonded to the first magnetic layer.
Inventors
- 👤 Shigeru Tsunashima
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-03 17:24
CPC Classifications
G; G11; G11B; G11B11/00; G11B11/10; G11B11/105; G11B11/10582; G11B11/10586; G11B11/10589; G11B11/10591
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
56 words
An optical magnetic recording medium comprising: a first magnetic layer vertically magnetizable comprising a rare earth-iron group amorphous alloy; and a second magnetic layer having lower coercive force than said first magnetic layer comprising a rare earth-iron group amorphous alloy containing light rare earth, said second magnetic layer being exchange bonded to said first magnetic layer.
Claim 2
Dependent Claim
56 words
An optical magnetic recording medium comprising: a first magnetic layer vertically magnetizable comprising a rare earth-iron group amorphous alloy; and a second magnetic layer having lower coercive force than said first magnetic layer comprising a rare earth-iron group amorphous alloy containing light rare earth, said second magnetic layer being exchange bonded to said first magnetic layer.
Claim 3
Dependent Claim
27 words
An optical magnetic recording medium according to Claim 1, wherein said first magnetic layer and said second magnetic layer are laminated alternately in two or more sets.
Claim 4
Dependent Claim
31 words
An optical magnetic recording medium according to Claim 2, wherein said first magnetic layer and said second magntic layer each have a thickness in the range from 30 to 300 Å.
Claim 5
Dependent Claim
31 words
An optical magnetic recording medium according to Claim 3, wherein said first magnetic layer and said second magnetic layer each have a thickness in the range from 50 to 150 Å.
Claim 6
Dependent Claim
57 words
An optical magnetic recording medium according to Claim 1, wherein said second magnetic layer has a composition shown below: LR X (Fe 1-Y Co Y ) 1-X wherein LR is one or more element selected from Nd, Pr, Ce and Sm, and X and Y are 0.1 ≦ X ≦ 0.4 and 0 ≦ Y ≦ 1.
Claim 7
Dependent Claim
25 words
An optical magnetic recording medium according to Claim 5, wherein X and Y are 0.2 ≦ X ≦ 0.3 and 0.2 ≦ Y ≦ 1.
Claim 8
Dependent Claim
17 words
An optical magnetic recording medium according to Claim 6, wherein Y is 0.2 ≦ Y ≦ 0.8.
Claim 9
Dependent Claim
22 words
An optical magnetic recording medium according to Claim 1, wherein said second magnetic layer comprises either one of Nd-Fe-Co, Nd-Co and Nd-Fe.
Claim 10
Dependent Claim
78 words
An optical magnetic recording medium according to Claim 1, wherein said second magnetic layer has a composition shown below: LR X HR Y (Fe 1-Z Co Z ) 1-X-Y wherein LR is one or more element selected from Nd, Pr, Ce and Sm, HR is one or more element selected from Gd, Tb, Dy and Ho, and X, Y and Z are 0.1 ≦ X ≦ 0.4, 0.05 ≦ Y ≦ 0.3 and 0 ≦ Z ≦ 1.
Claim 11
Dependent Claim
31 words
An optical magnetic recording medium according to Claim 9, wherein X, Y and Z are 0.1 ≦ X ≦ 0.3, 0.05 ≦ Y ≦ 0.2 and 0.2 ≦ Z ≦ 1.
Claim 12
Dependent Claim
17 words
An optical magnetic recording medium according to Claim 10, wherein Z is 0.2 ≦ Z ≦ 0.8.
Claim 13
Dependent Claim
25 words
An optical magnetic recording medium according to Claim 9, wherein said second magnetic layer has a thickness in the range from 100 to 500 Å.
Claim 14
Dependent Claim
25 words
An optical magnetic recording medium according to Claim 12, wherein said second magnetic layer has a thickness in the range from 150 to 300 Å.
Claim 15
Dependent Claim
22 words
An optical magnetic recording medium according to Claim 1, wherein said first magnetic layer comprises either one of Tb-Fe-Co, Dy-Fe-Co and Tb-Dy-Fe-Co.
Claim 16
Dependent Claim
25 words
An optical magnetic recording medium according to Claim 1, wherein said first magnetic layer has a thickness in the range from 100 to 2000 Å.
Claim 17
Dependent Claim
25 words
An optical magnetic recording medium according to Claim 15, wherein said first magnetic layer has a thickness in the range from 500 to 1000 Å.
Claim 18
Dependent Claim
23 words
An optical magnetic recording medium according to Claim 1, wherein said second magnetic layer has coercive force of about 1 KOe or less.
Claim 19
Dependent Claim
22 words
An optical magnetic recording medium according to Claim 1, wherein said first magnetic layer has coercive force of several KOe or higher.
Claim 20
Dependent Claim
22 words
An optical magnetic recording medium according to Claim 18, wherein said first magnetic layer has coercive force of 5 KOe or higher.
Claim 21
Dependent Claim
22 words
An optical magnetic recording medium according to Claim 19, wherein said first magnetic layer has coercive force of 10 KOe or higher.
Claim 22
Dependent Claim
31 words
An optical magnetic recording medium comprising a first magnetic layer and a second magnetic layer having a lower coercive force than the first magnetic layer and containing a light rare earth.
Claim 23
Dependent Claim
31 words
An optical magnetic recording medium comprising a first magnetic layer and a second magnetic layer having a lower coercive force than the first magnetic layer and containing a light rare earth.
References Cited (Backward Citations)
EP0258978A2
Cited
EP0291248A2
Cited
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